[问答题]
The question is basesegdl;d(+ dl0p4 f s7pqj2s6s+mh)e;wvt h-dd on the second passage you have just heard.
参考答案: The function of the human immune system.
The cause of various auto-immune diseases.
The viruses that may infect the human immune system.
The change in people's immune system as they get older.
